In existing Inductive Power Transfer (IPT) applications using a flat pick-up on a floor or roadway, there are two pick-up geometries in common use.
The first arrangement is used with Automated Guided Vehicles (AGV's), and is sensitive to the vertical component of the magnetic flux produced by the currents in the primary conductors (commonly known as the track conductors). Ideally it sits directly above the track conductors, giving the maximum output when the pick-up coil is perfectly aligned between the track conductors. Any misalignment of the pick-up reduces the output from the pick-up coil, which falls to zero at a misalignment of roughly half of the distance between the track conductors.
The second arrangement is sensitive to the horizontal component of the flux produced by the current in the track, and gives the maximum output when the coil is directly over either one of the track conductors. The output falls to zero when the coil is approximately mid-way between the conductors.
When the IPT application is a moving vehicle, neither of these pick-up geometries is ideal as relatively small alignment errors cause the output to fall so that power to the vehicle is lost.